The inventive concept relates generally to electronic memory technologies. More particularly, the inventive concept relates to management of memory blocks in nonvolatile memory devices.
Nonvolatile memory devices are widely used as storage media in applications ranging from personal electronics to industrial equipment. Nonvolatile memory devices retain stored data when disconnected from power, and they may also provide relatively high storage capacity and efficient performance.
Flash memory is a popular form of nonvolatile memory that can be found in a wide variety of electronic devices, with examples including portable electronics such as cellular phones, tablet computers, cameras, and memory fobs, as well as solid state drives and other mass data storage devices. In addition to providing relatively high storage capacity and efficient performance, flash memory can be electrically programmed and erased, and it may provide benefits of relatively low power consumption and an ability to withstand physical shock.
One potential drawback of flash memory and certain other forms of nonvolatile memory is that memory cells may not be overwritten without erasing an entire memory block (abbreviated as “block”). Accordingly, where a program operation is requested for an already programmed logical page, the corresponding physical page is typically invalidated, a new physical page (or physical address) is assigned to the logical page, and the requested program operation is carried out on the new physical page to store the logical page. Unfortunately, this can lead to a significant amount of unavailable memory space in the form of invalidated physical pages. As a result, garbage collection may be required on an occasional basis to free up some of the unavailable memory space.
In a typical garbage collection operation, a memory block having several invalid pages is freed up by moving all of its valid data to another memory block and then performing an erase operation on the memory block. A significant drawback of conventional garbage collection operations, however, is that they may require a significant amount of time, which can reduce the overall performance of a nonvolatile memory device. Consequently, there is a general need to reduce the amount of time required to perform garbage collection operations in nonvolatile memory devices.